FreeBSD Release Engineering for Third Party Software
Packages

StevePrice

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Last modified on 2013-11-13 by hrs.

Abstract

This paper describes the approach used by the FreeBSD
ports management team to produce a high quality package set
suitable for official FreeBSD release media. This document is
a work in progress, but eventually it will cover the process
used to build a clean package set on the FreeBSD.org “Ports
Cluster”, how to configure any other set of machines as a
ports cluster, how to split up the packages for the release
media, and how to verify that a package set is
consistent.

1.Â Building packages from the Ports Collection

The FreeBSD Ports
collection is a collection of over 24,000
third-party software packages available for FreeBSD. The Ports Management Team <portmgr@FreeBSD.org>
is responsible for maintaining a consistent ports tree that can be used
to create the binary packages that accompany a given FreeBSD
release.

1.1.Â The Ports Cluster

In order to provide a consistent set of third-party
packages for FreeBSD releases, every port is built in a
separate chroot environment, starting with an empty
/usr/local and
/usr/X11R6. The requisite dependencies
are installed as packages before the build proceeds. This
enforces consistency in the package build
process. By starting the package build in a pristine
environment, we can assure that the package metadata (such as
required dependencies) is accurate. This way, we will never
generate packages that might work on some systems and not on
others depending on what software was previously
installed.

The “Ports Cluster” for the x86 architecture
currently consists of a master node (Dual PentiumÂ® III 733MHz)
and 8 slave nodes (PentiumÂ® III 800MHz) to do the actual
package builds. With this configuration, a complete package
build takes over 24 hours. These machines are co-located with
the other FreeBSD Project equipment at Yahoo's corner of
Exodus in Santa Clara, CA.

The “Ports Cluster” for the Alpha
architecture consists of 7 PWS 500A machines donated by Compaq
and also co-located with Yahoo's facilities.

2.Â The Package Split

For FreeBSD 4.4 over 4.1 gigabytes of packages were created.
This causes a problem for CDROM distributions because we would
like to ship as many packages as possible without making the
user insert another disc to satisfy dependencies. The solution
is to create “clusters” of like packages with
similar dependencies and group these onto specific discs. This
section describes the software and methodology used to create
those package sets for the official FreeBSD release
discs.

The scripts and other files needed to produce a package
split can be found in the CVS tree in
ports/Tools/scripts/release.
Copy this directory to a machine that has enough free disk
space to hold 2 to 3 times the size of the package set that you
wish to split.

The following scripts are present in this directory:

config

This file contains the free space on each disc
and whether packages, distfiles, or both are allowed on any
given disc. The first column is the disc name. It must be
of the form disc[0-9a-z]. Currently it is set up
to allow for 10 discs (4 for the release set and 6 for the toolkit).
There is an implied extra disc called “scratch” where
all of the remaining distfiles/packages land if they do not fit
elsewhere. The second column can be either a 1 or 0, where 1
says that it is okay to place packages on this disc. The
third column works the same way, but it controls
whether distfiles are placed on this disc. The last column
denotes the number of bytes of free space on a
disc.

doit.sh

This is the workhorse. Once you have all the
files in place and things properly configured this script
directs the process of splitting packages. Beware it is
interactive so you need to keep an eye on it as it runs.
More details on what happens in this script will
follow.

checkdeps.pl

Makes sure all packages dependencies are
satisfied given an INDEX file and a directory
of packages.

oneshot.pl

This is where all the magic (and I use that
term loosely as it is mostly just a brute force approach)
happens. Given a list of required packages for each disc
and a set of packages/distfiles this is the script that
places a package or distfile on a disc along with all of its
dependencies.

print-cdrom-packages.sh

This file is a copy of
src/release/scripts/print-cdrom-packages.sh
from the release you are working on.

scrubindex.pl

This script removes lines from an
INDEX file for packages that are not present.
It also removes the XFree86™ dependencies. NOTE: you will need to
tweak the value of the xdep variable to make sure
the version number is correct.

setup.sh

This is a helper script that I use on the
ports building cluster to grab a copy of the ports tree and the
matching set of the packages/distfiles.

Here is a checklist of things you will need to check or
configure before going any further.

Edit config to denote the
number of discs you have, their sizes, and whether you want
them want to contain packages, distfiles, both, or
neither.

Make sure you remove the gen
directory if there is an old one laying around. This directory
contains working files that will only be valid for the current
split.

On your first pass through a split it is best to
fake the copying of packages and distfiles. This will save
both time and disk space while you do a couple of trial runs to
make sure things fit, etc. In the
oneshot.pl set the fake
variable to 1 and instead of actually copying the files it will
touch(1) them. Be sure you turn this off or set
fake to 0 before you give the resultant discs to
the person that will be mastering the discs otherwise they will get a
directory full of zero-sized files.

Make sure you have a recent copy of the
print-cdrom-packages.sh and that it is
from the correct release.

Check to make sure the XFree86™ dependency in
scrubindex.pl has the correct
version number. You will also need to make sure this value is
correct in doit.sh as
well.

Next you will need to get a copy of the ports tree, packages,
and distfiles from a recent build on the package cluster. See
the setup.sh for a working example
but essentially here is what needs to be done.

Grab a copy of ports.tar.gz
and extract it into the ports directory alongside
doit.sh and the
scripts directory.

Remove the packages/distfiles directories or
symlinks. Bento has these as symlinks and you will have mixed
results if you do not get rid of them before
proceeding.

Create a new ports/packages directory and copy
the package set from the package building
cluster.

Create a new ports/distfiles directory and copy
the distfiles from the package building cluster. NOTE: if you
do not want any distfiles simply create the directory and leave
it empty. This directory must be present even if it does not
contain anything.

Now we are finally ready for the fun task of actually
splitting the packages. You start the processing by running
./doit.sh. Here is what it does the first
time you run it.

Create a list of the restricted (can not be on the
master FTP site) ports.

Asks you if you would like to remove the restricted
ports. Most of the time you will want to answer (y)es
here.

Create a list of the packages/distfiles that
can not be put on the discs.

Asks you if you would like to remove the
non-cdromable packages/distfiles. Most of the time you will
want to answer (y)es here.

Copies the INDEX from the
ports directory to the gen
directory. In doing so it removes the lines for ports
where the packages do not exist. It also checks to make sure
that all of the required dependency packages are
present.

Create a list of packages that are required on
each disc.

Asks you if you would like to populate the discs.
After populating each disc it will check for missing
dependencies, scrub the INDEX file, and create the
CHECKSUM.MD5 file.

Check to make sure the required packages made it
on each disc and gives you a summary of the sizes of each
disc.

After going through this the first time if you are lucky
enough that all of the required packages built and fit on each
disc. All you need to do is set fake to 0 in
oneshot.pl and re-run
./doit.sh. The second and subsequent times
around it will skip steps 1-5 above. If you want to re-run any
of those steps refer to doit.sh for which files
need to be removed to not short-circuit those steps. If you want to
repeat all of these steps then the easiest way is to rm -rf
gen.

Upon successful completion the packages/distfiles will be in
the disc* directories and the leftover will
be in the scratch directory.

What to do if things go wrong? Here is some common gotchas
and workarounds.

Missing required packages

This is a pretty common occurrence. You will
either need to wait for a new set of packages where the
missing packages were built or get someone to re-start the
package build for you. Do not attempt to build
the missing packages on your own machine and add them into the fray.
While you might be able to get away with this if you are
extremely careful the vast majority of the time you will miss
some little detail and the simple process of adding a
package could make hundreds of others come up mysteriously
broken.

Required packages will not fit

This happens on occasion too and is relatively
easy to fix. Simply edit
print-cdrom-packages.sh to move
packages around until they fit. Yes this is an iterative
process and one of the reasons why you should enable
fake in oneshot.pl until you
have gotten things the way you want them. Re-run
./doit.sh after you made your
adjustments.

Required packages not on the right (or any) disc

This usually means you did not add them to
print-cdrom-packages.sh or you put them
on the wrong disc. This script is the gospel by which this
whole process determines where a package must be. If you
want to force a package to land on a particular disc this is
the only way to ensure that it will
happen.

If you get completely stuck and can not figure out why things
are borked or how to fix them then email Steve Price <steve@FreeBSD.org> for
assistance.